Signors to the badische anilin and soda fabrik



UNITED STATES PATENT EEicE.

RUDOLPH KN'IETSOH AND PAUL SEIDEL, OF LUDVVIGSHAFEN, GERMANY, AS- STGNORS TO THE BADISCHE ANILIN AND SODA FABRIK, OF SAME PLACE.

INDOXYLIC ACID AND PROCESS OF MAKiNG IT.

SPECIFICATION forming part of Letters Patent No. 546,165, dated September 10, 1895.

App 5185 May 17, 1895- Serial No. 549,709. (No specimens.) Patented in France November 12, 1894, No. 206,982 in Belgium November 17, 1894, No. 112,74'i; in Italy December 6, 1394, XXIX, 37,665, and LXXIII, 498, and in Austria Decamber 24, 3.5394 1%. 44/ 6,512.

'0 (632 whom, it may concern/.- white in ice-water and precipitating the in Be it known that we, RUDOLPH KNIETSCH, doxylic acid by the addition of sulfuric or hydoctor of philosophy,asubject of the King of droohloricacid or a stronger organic acid. Prussia, German Emperor, and PAUL SEIDEL, Indoxylic acid, as heretofore obtained by the 5 doctor of philosophy, 2. subject of the King of process of Baeyer, and as described in the Saxony, residing at Ludwigshafen-on-thetext-books, contains more or less combined Rhine, in the Kingdom of Bavaria and Emhaloid elements, as bromin or chlorin; but pire of Germany, have invented new and useindoxylic acid as obtained by our process is 5 5 ful Improvements in the Manufacture of a entirely free from haloid elements.

[0 New .lndoxylic Acid, (for which patents have The following example will serve to illusbeen obtained in France, No. 206,982, (certifitrate the manner in which our invention can eat daddition,) dated November 12, 1894:; in best be carried into practical effect. The Austria, i4. 6,512, dated December 24, 1894;; parts are by weight. in Belgium, No. 112,744., dated November 17, Example: Mix about ten (10) parts of so- 1 5 189%, and in Italy, XXIX, 37,-365,LXXHI,498, dium phenyl glycocoll ortho carboxylate, dated December 6, 1894,) of which the followwhich must be quite neutral and thoroughly ing is a specification. dried with about twenty (20) parts of caustic Our invention relates to the manufacture soda, which must also be as free from water of a new commercial product suited for use in as possible. Grind these two ingredients to- 20 printing indigo-blue shades on textile fabrics. gether, so that they become thoroughly mixed,

In the Letters Patent No. 534,560, granted to and spread the fine powder so obtained in a Karl lleumanmthere is described the producthin layer. Then heat uniformly to a temtion of a new artificial indigo-white from perature of about two hundred and forty to phenyl-glycocoll-orthocarboxylic acid by two hundred and sixtyfive degrees centi- 2 treating with alkali. This is described as grade, (24.0-265G.) Throughout the operaconsisting of an intimate combination or mixtion the atmospheric air must be excluded as ture of unaltered alkali or alkaline earth with far as conveniently possible. This can be a body having the nature ofaleuco compound done, for example, by conducting the operaand with other products of the reaction. We tion in an atmosphere of an indifferent gas,

30 have found that the nature of this contained such as nitrogen, hydrogen, or the like. As leuco body varies according to the conditions the mass does not melt, the period of heating under which the reaction is effected, and that depends upon the thickness of the layer. In usually the leuco body is a mixture of ingenerah'from half an hour to one hours heatdoxyl and an indoxylie acid in the form of aling after the temperature mentioned is at- 3 5 kaline salt. We have discovered modificatained, is requisite. Allow the mass to cool. tions of the process for treating the phenyl- It should then possess a uniform lemon-yelglycocoll-ortho-carboxylic acid with alkalies low color throughout. The presence of a whereby it is possible with certainty to prowhitish. mass in the interior indicates that duce an artificial indigo-white containing inthe reaction is not complete and the heat must 4c doxylic acid only, to the practical exclusion of be maintained longer. Next grind about fifty indoxyl. This is effected by the use of caus- (50) parts of the artificial indigdwhite so obtic soda in the treatment of the phenyl-glycotained to powder and add it to a mixture of coll-ortho-carboxylic acid and at a temperaabout four hundred (400) parts of ice and go ture rising to about 240 to 265 centigrade. about one hundred and seventy -five- 45 From this artificial indigo-white we prepare part-s of dilute sulfuric acid containing about and isolate our new indoxylic acid. This is twenty-two per cent. (22%) real acid (H 80 effected by dissolving the artificial indigo- The indoxylic acid separates out as a prein alcohol and ether.

cipitate. Filter and wash with ice-cold water. In the moist state the acid is unstable, but becomes more stable after drying. Drying must be effected at a moderate heat (not above 50 centigrade) by spreading the material overa large surface. It is advantageous, but not necessary, to exclude the oxygen of the atmosphere.

Our new commercial product is a gray powder but slightly soluble in cold water, soluble It is readily soluble in alkaline water, and the solution turns blue from formation of indigotin on exposure to the action of the atmospheric oxygen.

This new product diifers from the substance heretofore known as indoxylic acid, and described as such, in the fact that it is 00111- pletely free from combined halogen, as can be seen by oxidizingto indigotin in alkaline solution, filtering off the indigotin, washing and testing the indigotin for halogens in the usual way'for instance, by treating with caustic lime, dissolving in nitric acid and testing for the haloid elements by means of nitrate of silver. The old indoxylic acid described in literature has existed solely as a scientific curiosity, and from its costliness and difficulty of production could never be commercially manufactured.

. Now, what we claim is 1. Asanew product theindoxylic acid which can be produced by the reaction of phenylglycocoll-ortho-carboxylic acid with caustic soda, and which is a gray powder but slightly soluble in cold water, soluble in alcohol and treating phenyl glycocoll ortho carboxylic acid with caustic soda at about240 to 265 centigrade, then treating the melt with ice cold dilute acid, then filtering and washing the precipitate, substantially as described.

In testimony whereof we have hereunto set our hands in the presence of two subscribing witnesses.

RUDOLPH KNIETSCH. PAUL SEIDEL.

\Vitnesses:

ERNEST F. EHRHARDT. ADOLPH RENTLINGER. 

